There has been much demand for analysis of the structures of high molecular compounds typified by protein, with advanced requests. That is, there have been many studies for analyzing the nature and function of protein as well as its structure and utilizing the results for medical and pharmaceutical sciences. X-ray diffraction is best known as a method of analyzing protein microstructure. X-ray diffraction requires the creation of a single crystal sample but enables high-resolution measurement, which is described for example in Medical Tribune (VOL. 39, p. 36, 2006). Other apparatuses for analyzing protein microstructure include a three-dimensional transmission electron microscope and an atomic force microscope.
At present, in the field of magnetic recording, hard disk bit lengths reach a 30-nm level. Accordingly, minute bit distortion may cause severe noise, and there is a need for recording for controlling bit shapes more accurately than ever. However, there are few methods for evaluating whether a recording bit shape is distorted, and expectations are rising for magnetic domain observation with high resolution less than 10 nm. Both in perpendicular magnetic recording which has recently been commercialized and in longitudinal magnetic recording which has conventionally been employed, such bit shape evaluation is important. Since crystal grain sizes are currently less than 10 nm, a resolution of a few nm is required for magnetic domain observation. Among current general-purpose high-resolution magnetic domain observation apparatuses, a Lorentz electron microscope can provide the highest resolution. In the Lorentz electron microscope, an electron beam is acted upon by Lorentz force due to a leakage magnetic field from a sample, and a deflection thereof makes a signal. Therefore, in theory, only the magnetization component perpendicular to the incident direction of an electron beam is detected.
Further, two electron beam technologies important to the invention will be described. One is electron beam holography. This is utilized as a method for measuring an electromagnetic field in a minute area. An electron beam changes its phase by an electromagnetic field in a vacuum or in a substance. An ordinary electron beam detection apparatus can record only the intensity distribution of the electron beam, and cannot measure the phase of the electrons without any processing. In order to record the phase change of the electron beam that has passed through the electromagnetic field, it is necessary to convert the phase change into the intensity distribution. In the electron beam holography method, an electron beam biprism apparatus records the intensity distribution of a striped interference pattern generated by the superposition of an electron beam that has passed through a vacuum near the sample (reference wave), thereby achieving this conversion. Measurement methods using the electron beam holography are disclosed, for example, in JP-A No. 64 (1989)-065762, JP-A No. 05 (1993)-322839, and JP-A No. 05 (1993)-323859.
The other is a spin-polarized electron source. Among others, attention is being given to a spin-polarized electron source of a type that irradiates a semiconductor such as GaAs with circularly polarized light, which is described for example in Solid State Communication, Vol. 16, p. 877, 1975 by G. Lanpel et al. An invention for improving spin polarization by using a distorted semiconductor is disclosed in JP-A No. 07 (1995)-320633, and a similar description is written in Physics Letters A, Vol, 158, p. 345, 1991 by Nakanishi et al.